Question

complete each step to show that the sum of the measures of \\( \angle 1, \angle 2 \\), and \\( \angle 3 \\) is \\( 180 ^ { \circ } \\). step 1: \\( m \angle 1 = m \angle 4 \\) and \\( m \angle 2 = m \angle 5 \\) because alternate interior angles are congruent. step 2: \\( m \angle 4 + m \angle 3 + m \angle 5 = 180 ^ { \circ } \\) because the three angles form a straight angle. step 3: \\( m \angle 1 + m \angle 3 + m \angle 2 = 180 ^ { \circ } \\) because you can substitute? for \\( m \angle 4 \\) and you can substitute? for \\( m \angle 5 \\).

Explanation:

Step 1: Recall Step 1's Relationship

From Step 1, we know \( m\angle1 = m\angle4 \) and \( m\angle2 = m\angle5 \).

Step 2: Substitute in Step 2's Equation

In Step 2, we have \( m\angle4 + m\angle3 + m\angle5 = 180^\circ \). To get \( m\angle1 + m\angle3 + m\angle2 = 180^\circ \), we substitute \( m\angle1 \) for \( m\angle4 \) (since \( m\angle1 = m\angle4 \)) and \( m\angle2 \) for \( m\angle5 \) (since \( m\angle2 = m\angle5 \)).

Answer:

For the first "?", substitute \( m\angle1 \); for the second "?", substitute \( m\angle2 \).